CN105140057A - Nitride enhanced copper-based electrical contact composite material - Google Patents

Abstract

The invention relates to a nitride-reinforced copper-based electrical contact composite material, the composition of which is represented by weight percent: 0.5-4% nitride, 0.5-4% bismuth, 0.1-0.6% rare earth yttrium, 0.5-2.5% yttrium oxide , and the rest are copper and other unavoidable impurities; among them, the nitride is titanium nitride or aluminum nitride. The material of the invention is made through the preparation methods of atomization powder making, batching, mixing, and vacuum hot pressing and sintering. The material of the present invention uses copper as the matrix, and the main raw material resources are abundant, and the nitride is uniformly dispersed and distributed on the copper base material in the form of a reinforcing phase, which improves the degree of miniaturization of the internal structure of the material, and the material not only has good electrical and thermal conductivity, Welding resistance, arc ablation resistance, and excellent mechanical properties and wear resistance, can meet the basic requirements for materials such as electrical contacts, and can be applied to power switches, relays, and DC contactors with medium and low electrical loads , Air switch and other low-voltage electrical appliances. Compared with silver-based electrical contact materials, the cost performance is more advantageous.

Description

A kind of nitride reinforced copper-based electrical contact composite material

technical field

The invention relates to a nitride-reinforced copper-based electrical contact composite material, in particular to a method for preparing a copper-based electrical contact material by adding an appropriate amount of nitrides, which can be applied to power switches, relays, DC contactors, and converters with medium and low electrical loads. In low-voltage electrical appliances such as appliances.

Background technique

Weak current contact elements are the key components of instruments and meters, which play an important role in the life and reliability of instruments and meters. In order to ensure the reliability of weak current contacts, precious metal silver and its alloy materials are widely used at home and abroad. In recent years, in order to reduce the loss of silver metal, people are constantly seeking new ways of saving and replacing silver. The electrical and thermal conductivity of copper is the closest to that of silver, so copper is the most suitable element to replace silver as a conductive material, but the main obstacle for copper as an electrical contact material is that the surface of copper-based materials is easily oxidized under atmospheric conditions, and Its oxides (CuO and Cu ₂ O) have very low electrical conductivity, which sharply increases the contact resistance of the element, makes the material easy to generate heat during use, and directly affects the working reliability and life of the electric switch. Copper alloys are difficult to apply as contact materials. Studies have shown that the phenomenon of electrofusion welding and arc erosion generated during the opening and closing process of electrical contacts is extremely complex. Under the combined effects of arc energy, contact pressure and environmental factors, the contact surface is heated, melted, vaporized, flowed and solidified And other physical metallurgical processes, resulting in melting, softening, splashing, flow and cracks on the contact surface. Therefore, in addition to good physical properties, contact materials are required to have excellent mechanical properties and chemical stability. However, metal copper is easy to oxidize compared to silver, and the oxidation product has a large resistance. If pure copper is used as an electrical contact material, the contact resistance will rise suddenly, especially in the process of breaking and closing the electrical contactor, electrofusion welding and arc erosion The phenomenon is serious, and the life of the contact material is greatly shortened.

Contents of the invention

The purpose of the present invention is to provide a copper-based electrical contact composite material that is low in price, high in electrical conductivity and thermal conductivity, low and stable in contact resistance, good in welding resistance, good in oxidation resistance and mechanical properties, and easy to prepare. It can replace silver-based electrical contact materials with high raw material prices. Another object of the present invention is to provide a preparation and molding method of the above-mentioned material.

The present invention is achieved through the following measures:

The nitride-reinforced copper-based electrical contact composite material of the present invention has a formula expressed in weight percent: 0.5-5% nitride, 0.5-4% bismuth, 0.1-0.6% rare earth yttrium, 0.5-2.5% yttrium oxide, and the rest It is copper and other unavoidable impurities; among them, the nitride is titanium nitride or aluminum nitride.

The preferred composition of the nitride-reinforced copper-based electrical contact composite material of the present invention is: 1.5% titanium nitride, 2% bismuth, 0.2% yttrium, 1% yttrium oxide, and the rest is copper and other unavoidable impurities.

A kind of nitride reinforced copper-based electrical contact composite material of the present invention, its specific steps are:

(1) First, the rare earth yttrium and copper are made into yttrium-copper alloy powder with a yttrium content of 0.1-0.6% by the atomization method, and the copper-yttrium alloy powder with a particle size of 100-300 meshes is prepared according to the composition ratio. The bismuth powder, yttrium oxide powder, and nitride powder are mixed by ball milling for 1-3 hours, and the rotating speed of the ball mill is 150-300 revolutions per minute.

(2) Vacuum hot pressing and sintering the uniformly mixed powder. The pressure is 20-50MPa, the sintering temperature is 750-950°C, the pressure is applied when the predetermined temperature is reached, and the holding time is 1-3 hours. When the sintering temperature is higher, the holding time can be appropriately shortened. Release the pressure when the temperature drops to 300-500°C. The heating rate is 5-15°C/min, and samples are taken after cooling to 200°C. During the whole sintering process, keep the vacuum degree in the furnace lower than 1×10 ^-2 Pa.

In the preparation method of the present invention, the balls used in the ball mill are corundum balls, and the ball-to-material ratio is 15:1.

The copper-based electrical contact composite material of the invention is mainly used in low-voltage electrical appliances such as power switches, relays, DC contactors, and air switches with medium and low electrical loads. Copper is selected as the matrix. Compared with silver, copper is cheap and abundant in resources. Its electrical and thermal conductivity, welding resistance, current corrosion and friction characteristics are comparable to silver, which can meet the requirements of the electrical contact material matrix. Considering the requirements of contact material mechanics and electrical contact performance, low-boiling metal bismuth is used as the arc-stopping component; rare earth elements are added to improve oxidation resistance and comprehensive performance; yttrium oxide is added to improve the arc ablation resistance of the material; nitrogen is added The main purpose of the nitride (titanium nitride or aluminum nitride) is: during the sintering process, the nitride can effectively prevent the coarsening of the copper grains, make the matrix grains finer, improve the microstructure of the internal structure of the material, and make the electrical contact The material is not easy to weld during use, thereby improving the anti-welding performance and mechanical properties of the material.

The composite material prepared by the method of the present invention has high material density, excellent electrical and mechanical properties, good welding resistance and oxidation resistance, stable contact resistance, good electrical conductivity, and arc ablation resistance. It has excellent performance, simple preparation process, and can be molded at one time. It is a contact material especially suitable for frequent opening and closing of medium and low voltage electrical appliances.

Detailed ways

Example 1:

The composition weight ratio of the material in this embodiment is: 2% bismuth, 0.5% titanium nitride, 0.2% rare earth yttrium, 1% yttrium oxide, and the balance is copper.

First, according to the composition ratio, the rare earth yttrium and copper are made into copper-yttrium alloy powder with a yttrium content of 0.05% and a particle size of 100-300 mesh, and then adding bismuth powder with a particle size of 200 mesh for ball milling. The ball milling time is 2 hours. The balls used in the ball mill are corundum balls, the ball-to-material ratio is 15:1; then 0.5% titanium nitride and 1% yttrium oxide are added for mechanical powder mixing; after mixing evenly, they are sintered in a vacuum hot-press furnace, and the pressure is pressed The sintering temperature is 20MPa, the sintering temperature is 800°C, the pressure is applied when the predetermined temperature is reached, the holding time is 2 hours, and then the pressure is released when the temperature is lowered to 400°C. The heating rate was 10°C/min before 400°C, 5°C/min after 400°C, and samples were taken after cooling to 200°C. During the whole sintering process, keep the vacuum degree in the furnace lower than 1×10 ^-2 Pa. Through the above process, a copper-based electrical contact composite material or part is made.

Basic properties of this material: Density 99.36%; Resistivity 3.08μΩ·cm; Hardness 48HB; Oxidation weight gain of 1.25mg/cm ² (for pure copper 5mg/cm ² ) oxidized for 20h under atmospheric conditions at 400°C.

Example 2:

The composition weight ratio of the material in this embodiment is: 2% bismuth, 1.5% titanium nitride, 0.2% rare earth yttrium, 1% yttrium oxide, and the balance is copper.

Ball milling, powder mixing, and vacuum hot-press sintering were carried out according to the same preparation process steps and parameters as in Example 1. Through the above process, a copper-based electrical contact composite material or part is made.

The basic properties of this material: Density 99.46%; Resistivity 2.97μΩ·cm; Hardness 57HB; Oxidation weight gain 1.08mg/cm ² under 400℃ atmospheric conditions for 20h.

Example 3:

The composition weight ratio of the material in this embodiment is: 4% bismuth, 1.5% titanium nitride, 0.2% rare earth yttrium, 1% yttrium oxide, and the balance is copper.

Ball milling, powder mixing, and vacuum hot-press sintering were carried out according to the same preparation process steps and parameters as in Example 1. Through the above process, a copper-based electrical contact composite material or part is made.

The basic properties of this material: Density 98.76%; Resistivity 3.75μΩ·cm; Hardness 60HB; Oxidation weight gain 2.25mg/cm ² under 400℃ atmospheric conditions for 20h.

Example 4:

The composition weight ratio of the material in this embodiment is: 2% bismuth, 5% titanium nitride, 0.2% rare earth yttrium, 1% yttrium oxide, and the balance is copper.

Ball milling, powder mixing, and vacuum hot-press sintering were carried out according to the same preparation process steps and parameters as in Example 1. Through the above process, a copper-based electrical contact composite material or part is made.

Basic properties of this material: Density 98.86%; Resistivity 3.32μΩ·cm; Hardness 61HB; Oxidation weight gain 1.60mg/cm ² under 400℃ atmospheric environment for 20h.

Example 5:

The composition weight ratio of the material in this embodiment is: 2% bismuth, 0.5% aluminum nitride, 0.2% rare earth yttrium, 1% yttrium oxide, and the balance is copper.

Ball milling, powder mixing, and vacuum hot-press sintering were carried out according to the same preparation process steps and parameters as in Example 1. Through the above process, a copper-based electrical contact composite material or part is made.

Basic properties of this material: Density 98.25%; Resistivity 3.13μΩ·cm; Hardness 49HB; Oxidation weight gain of 1.30mg/cm ² oxidized for 20h at 400℃ atmospheric environment.

Embodiment 6:

The composition weight ratio of the material in this embodiment is: 2% bismuth, 1.5% aluminum nitride, 0.2% rare earth yttrium, 1% yttrium oxide, and the balance is copper.

Ball milling, powder mixing, and vacuum hot-press sintering were carried out according to the same preparation process steps and parameters as in Example 1. Through the above process, a copper-based electrical contact composite material or part is made.

Basic properties of this material: Density 98.75%; Resistivity 3.35μΩ·cm; Hardness 56HB; Oxidation weight gain of 1.62mg/cm ² under 400℃ atmospheric conditions for 20h.

Comparative test example:

Conduct an electrical contact strengthening test on the composite material of Examples 1-6 of the present invention and the silver-tin oxide electrical contact material. The test conditions are: resistive AC current 40A, voltage 54V, arcing frequency 26 times/min, test times 20000 times, the experimental results are shown in Table 1. From the comparison of samples 1, 2, and 4 in Table 1., it can be seen that: (1) As the amount of nitride increases in the range of 0-5%, the mass loss on the surface of the electro-strengthened sample gradually decreases, that is, the resistance to fusion welding The performance and arc ablation resistance are gradually enhanced; (2) The mass loss of the new material is significantly lower than that of the silver-tin oxide electrical contact material, and the mass loss of sample 3 (with a bismuth content of 4%) is the least, which also verifies The addition of bismuth is beneficial to improve the welding resistance of the material.

Table 1. Mass loss after electrical contact strengthening experiment of each sample

Specimen type Sample 1 Sample 2 Sample 3 Sample 4 Sample 5 Sample 6 Silver-tin oxide contacts Nitride content (wt.%) 0.5 TiN 1.5 TiN 1.5 TiN 5.0 TiN 0.5 AlN 1.5 AlN 0 Bismuth content (wt.%) 2 2 4 2 2 2 0 Mass loss (mg) 20 16 12 14 twenty two 19 95

Claims (7)

1. A nitride-reinforced copper-based electrical contact composite material. 2. A kind of nitride-reinforced copper-based electrical contact composite material according to claim 1, its composition formula is expressed as: 0.5-5% nitride, 0.5-4% bismuth, 0.1-0.6% rare earth yttrium, 0.5% -2.5% yttrium oxide, the rest is copper and other unavoidable impurities; the nitride is titanium nitride or aluminum nitride. 3. A kind of nitride-reinforced copper-based electrical contact composite material according to claim 2, its preferred composition is: 1.5% titanium nitride, 2% bismuth, 0.2% yttrium, 1% yttrium oxide, and the rest are copper and other unavailable Avoid impurities. 4. A kind of nitride-reinforced copper-based electrical contact composite material according to claim 1, characterized in that the following steps are adopted: (1) First, the rare earth yttrium and copper are made into yttrium-copper alloy powder with a yttrium content of 0.1-0.6%, and the copper-yttrium alloy powder with a particle size of 100-300 mesh, bismuth powder, oxide Yttrium powder and nitride powder are ball milled and mixed for 1-3 hours, and the speed of the ball mill is 150-300 revolutions per minute; (2) Vacuum hot pressing and sintering the uniformly mixed powder. The pressure is 20-50MPa, the sintering temperature is 750-950°C, the pressure is applied when the predetermined temperature is reached, and the holding time is 1-3 hours; when the sintering temperature is higher, the holding time can be appropriately shortened. Release the pressure when the temperature drops to 300-500°C. The heating rate is 5-15°C/min, and samples are taken after cooling to 200°C. During the whole sintering process, keep the vacuum degree in the furnace lower than 1×10 ^-2 Pa. 5. The preparation method according to claim 4, characterized in that in step (1), the copper-yttrium alloy powder has a particle size of 100-200 mesh. 6 . The preparation method according to claim 4 , wherein in step (1), the ball mill adopts a high-energy planetary ball mill, and the balls used are corundum balls, and the ball-to-material ratio is 15:1. 7. The preparation method according to claim 4, characterized in that in step (2), the pressing pressure is 20-50MPa, the sintering temperature is 750-950°C, and the holding time is 1-3 hours; when using When the sintering temperature is high, the holding time can be appropriately shortened.